THE PRODUCTION OF A DRIED AVOCADO (Persea americana) POWDER
Saheeda Mujaffar1*and Tsai-Ann Dipnarine2
1,2Faculty of Engineering, The University of the West Indies, Trinidad
1Email: saheeda.mujaffar@sta.uwi.edu *(Corresponding author)
2Email: tsaiann1@hotmail.com
Abstract:
This work investigated the technique of vacuum freeze drying of avocado pulp (Persea americana var. Pollock) to produce a dried cake which could be blended into a powder to be used in various food applications.Frozen, mashed avocado pulp samples were dried in a Benhay SB-4 vacuum freeze dryer. For comparison, fresh pulp samples were also oven-dried in a Unitemp drying cabinet at 60°C.Samples were dried until constant weight was achieved after which they were blended into powders and analysed.Analyses included determination of moisture content, water activity, pH and total soluble solids content, colour assessment, proximate analyses, physical properties, rehydration behaviour and a preliminary storage assessment.Drying data was used to generate rate and Moisture Ratio (MR) curves and thin layer models applied to the MR data.The moisture content and water activity values of the fresh pulp averaged 3.16 g H2O/g dry matter (76.0% wet basis) and 0.889, respectively.Samples were successfully dried in the freeze dryer to an average moisture content of 0.02 g H2O/g dry matter (2.1% wet basis) after 72h, and a final average water activity of 0.356.Drying occurred in the falling rate period and the drying rate constant (k1) averaged 0.2496 1/h. The Verma model was found to best fit the Moisture Ratio (MR) data.Compared with oven-dried samples, the freeze-dried samples dried to lower equilibrium moisture values, did not show any signs of browning and was higher in protein and fat content.The freeze-dried ‘cake’ was easier to blend to a light, free-flowing powder which easily rehydrated to a form which closely resembled fresh avocado puree.Freeze drying is therefore an attractive option to produce a high-quality Pollock avocado powder, without the use of heat or the application of chemical preservatives to preserve colour.
Keywords: Avocado, Freeze-drying, Oven-drying, Drying kinetics, Curve fitting
https://doi.org/10.47412/DDSD1316
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